HYPERPARATHYROIDISM AND MINIMALLY INVASIVE RADIOGUIDED PARATHYROIDECTOMY

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HYPERPARATHYROIDISM AND MINIMALLY INVASIVE
RADIO-GUIDED PARATHYROIDECTOMY

• Gavin O Brien
• Dept. of Surgery,
• Cork University Hospital

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INTRODUCTION

• Anatomy / Embryology
• Physiology
• Pathology
• Surgery

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ANATOMY / EMBRYOLOGY
The third branchial pouch gives rise to the
inferior parathyroid glands (dark blue) in close
association with the primordia of the the thymus
gland (orange). As the thymus descends to the
anterior mediastinum, parathyroids III follow
along, ultimately coming into contact with the
developing thyroid caudal to parathyroids IV
(yellow). The parathyroid glands derived from
pouch IV take a more direct route to come in
contact with the thyroid, and become the more
cephalad or superior glands. A portion of pouch
IV (light blue) contributes a lateral C-cell
component to the thyroid. The parathyroids
usually (80) lie near the posterolateral
capsule of the thyroid lobes.
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Anatomy / Embryology
The superior parathyroid glands are most commonly
found about the middle third of the thyroid lobe,
at the level of the cricothyroid junction, and
near the point where the recurrent laryngeal
nerve passes beneath the inferior pharyngeal
constrictor to enter the larynx

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Anatomy / Embryology
The inferior glands are usually found near the
lower pole of the thyroid lobe or below the lobe
in the thyro-thymic ligament. They commonly lie
below the inferior thyroid artery and anterior to
the recurrent laryngeal nerve.
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Anatomy / Embryology
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PHYSIOLOGY

• Parthyroid Hormone (PTH)
• Secreted by the Chief cells
• Levels are inversely conrolled by Ca2
• Effects
• Tubular reabsorption of Ca2
• Osteoclastic resorption of bone
• Intestinal absorption of Ca2
• Synthesis of 1-25DHCC (active Vit. D)
• Excretion of phosphate

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PATHOLOGY

• HYPERPARATHYROIDISM
• 1 1,000 prevalence
• F M 2 1
• Usually mild / asymptomatic

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Aetiology

• Primary ( PTH, normal or Ca 2 )
• Adenoma 90
• Hyperplasia 10
• Carcinoma lt 0.1
• Secondary ( PTH appropriate to low Ca 2 )
• Chronic Renal Failure
• Vitamin D Deficiency
• Tertiary
• Continued excess PTH secretion following
  prolonged secondary hyperparathyroidism.

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Parathyroid Adenoma inferior rim of normal
parathyoid tissue admixed with adipose tissue
cells
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Signs / Symptoms

• Asymptomatic (mild, lt 2.99)
• Bones, stones, abdominal groans, psychic moans

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Clinical Presentation
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Indications for Surgery
Symptomatic hyperparathyroidism Serum Ca 2 .
3.0 Reduced creatinine clearance by 30 Renal
stone on PFA Hypercalciuria ( gt400mg day 1
) Reduced cortical bone density Young patient ( lt
50 y.o.)
NIH Consensus Development Conference Statement -
Ann Intern. Med. , 1991
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SURGERY

• Success rate for surgical cure of primary
  hyperparathyroidism should exceed 95
• Until 10 years ago bilateral neck exploration.
• Radiological localization of hyperfunctioning PTH
  tissue was reserved for re-exploration surgery.

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SURGERY

• 99mTc sestamibi A new agent for parathyroid
  imaging.
• Coakley et al, Nucl Med Commun, 1989
• Clinical usefulness of intraoperative quick
  parathyroid hormone assay.
• Irvin,GL, Surgery, 1993
• Intraoperative identification of parathyroid
  gland pathology. A new approach utilizing a hand
  held gamma probe.
• Martinez DA, J Paedr. Surg, 1995

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SESTEMIBI SCANNING

• 99mTc 2-methyl-isobutyl-isonitrile radionuclide
  (Tc-sestemibi)
• Discovered in 1989 to be useful in imaging of
  parathyroid glands.
• Radioisotope uptake increases with gland weight.
• MIBI concentrated in tissues rich in
  mitochondria.
• Heart
• Salivary glands
• Thyroid glands
• Parathyroid glands

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• Denham et al, J Am Coll Surg, 1998
• Meta-analysis of 784 patients having preoperative
  sestemibi scans for exploration of primary HPT
• Sensitivity 91
• Specificity 99

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Clinical usefulness of intraoperative quick
parathyroid hormone assay.Irvin,GL, Surgery,
1993

• Intact PTH molecule has a half life measured in
  minutes
• Pre-op, pre-excision and 10 minute post-incision
• QPTH Assay should reduce by gt 50

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Intra-operative Gamma probe
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Intra-operative Gamma probe
Minimally invasive parathyroidectomy facilitated
by intraoperative nuclear mapping Norman J,
Surgery, 1997
15 patients with clearly a solitary adenoma on
Sestemibi Average incision 2.4 cm Mean operating
time 24 minutes 97 of patients discharged
within 2 hours of surgery Ex-vivo counts of 32
of background
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Advantages of MIRP

• Smaller incision
• 25 minutes
• L.A.
• Pain
• Cost
• Haematoma
• Recurrent laryngeal nerve injury
• Tissue planes
• Contralateral structures
• Less post-op hypocalcaemia

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Algorithm for MIRP
PTH / Calcium
Sestemibi scan
Solitary adenoma
Negative or MGD
Unilateral exploration
Bilateral exploration
gt50 iPTH
lt50 iPTH
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Summary

• Pre-operative quality imaging is essential for
  successful unilateral parathyroidectomy.
• Sestemibi is the gold standard
• 91 specificity
• Allows intra-op Gamma probe confirmation
• Minimally invasive parathyroidectomy has
  revolutionised adenoma surgery.

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? QUESTIONS ?